Java 存储和读取 oracle CLOB 类型字段的实用方法

Posted 2020-08-30 ..小树苗

import java.io.BufferedReader;
import java.io.IOException;
import java.io.Reader;
import java.io.StringReader;
import java.sql.Connection;
import java.sql.DriverManager;
import java.sql.PreparedStatement;
import java.sql.ResultSet;
import java.sql.SQLException;

import oracle.jdbc.OracleDriver;
import oracle.sql.CLOB;

public class ClobTest {
    String url = "jdbc:oracle:thin:@127.0.0.1:1521:orcl";
    String user = "his_xs";
    String pwd = "123456";
    String text = "这是要插入到CLOB里面的数据";

    private void clobImport() throws ClassNotFoundException, SQLException {
        // TODO Auto-generated method stub
        DriverManager.registerDriver(new OracleDriver());
        Connection conn = DriverManager.getConnection(url, user, pwd);// 得到连接对象
        String sql = "insert into clob_test(id,str) values (‘1‘,?)";// 要执行的SQL语句

        PreparedStatement stmt = conn.prepareStatement(sql);// 加载SQL语句
        // PreparedStatement支持SQL带有问号？，可以动态替换？的内容。
        Reader clobReader = new StringReader(text); // 将 text转成流形式
        stmt.setCharacterStream(1, clobReader, text.length());// 替换sql语句中的？
        int num = stmt.executeUpdate();// 执行SQL
        if (num > 0) {
            System.out.println("ok");
        } else {
            System.out.println("NO");
        }
        stmt.close();
        conn.close();
    }

    // 将字CLOB转成STRING类型
    public String ClobToString(CLOB clob) throws SQLException, IOException {

        String reString = "";
        Reader is = clob.getCharacterStream();// 得到流
        BufferedReader br = new BufferedReader(is);
        String s = br.readLine();
        StringBuffer sb = new StringBuffer();
        while (s != null) {// 执行循环将字符串全部取出付值给StringBuffer由StringBuffer转成STRING
            sb.append(s);
            s = br.readLine();
        }
        reString = sb.toString();
        return reString;
    }

    private void clobExport() throws ClassNotFoundException, SQLException,
            IOException {
        // TODO Auto-generated method stub
        CLOB clob = null;
        String sql = "select * from clob_test where id=1";
        DriverManager.registerDriver(new OracleDriver());
        Connection conn = DriverManager.getConnection(url, user, pwd);// 得到连接对象
        PreparedStatement stmt = conn.prepareStatement(sql);
        ResultSet rs = stmt.executeQuery();
        String id = "";
        String content = "";
        if (rs.next()) {
            id = rs.getString("id");// 获得ID
            clob = (oracle.sql.CLOB) rs.getClob("str"); // 获得CLOB字段str
            // 注释： 用 rs.getString("str")无法得到 数据 ，返回的 是 NULL;
            content = ClobToString(clob);
        }
        stmt.close();
        conn.close();
        // 输出结果
        System.out.println(id);
        System.out.println(content);
    }

    
    public static void main(String[] args) throws Exception {
        ClobTest a = new ClobTest();
        a.clobImport();
        a.clobExport();
    }

}